Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Patent
1984-04-13
1985-12-03
Kittle, John E.
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
430257, 430311, 430319, 430327, 430394, 156212, 156230, 156241, 156574, G03C 500, G03C 174
Patent
active
045566275
ABSTRACT:
Simplified clamshell type printed wiring board production apparatus employs a reusable thin flexible plastic film as a carrier for a photopolymer coating layer for covering part of the conductive layer of a printed wiring board with a photoproduced pattern of high resolution. For solder mask coatings, two superimposed layers of polymer with diverse characteristics are employed to give significant advantages of high resolution, low cost, less production time with unskilled labor, better adherence to bare copper conductors, better environmental and electrical properties, and low tooling costs, without problems of outgassing and without the necessity for heating and cooling cycles during lamination. Low cost liquid photopolymer coatings are used advantageously by screen transfer with a scanning squeegee in an air free bond over circuit traces of considerable thickness in the absence of a vacuum. Expensive phototools are protected from accumulation of dirt and wear by carrying polymer layers on the reusable thin plastic film, which also precludes the cost of disposable release sheet covers. Diverse characteristics in the respective superimposed polymer layers permits better adherence to bare copper and better solder mask coatings. Use of 100% solids polymers prevents outgassing problems. Use of liquid polymers permits air free surface contact over rough surfaces to avoid loss of resolution. Partial pre-exposure of the polymer layers before deposit on the wiring board provides better tenting capabilities and avoids thinning out over circuit traces.
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patent: 4260675 (1981-04-01), Sullivan
patent: 4332873 (1982-06-01), Hughes et al.
patent: 4388137 (1983-06-01), McCarty et al.
patent: 4424089 (1984-01-01), Sullivan
patent: 4506004 (1985-03-01), Sullivan
Hughes, Screen Printing of Microcircuits, Dan Mar Publishing Co., New Jersey, 1967.
Dees Jos,e G.
Kittle John E.
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